When trying to build fiber laser systems (including fiber amplifiers connected to their pump and seed sources), we have been frustrated by the lack of quick, snap-together connectors for high power fibers.
For example, although the SMA connector is suitable for high-power, multimode fiber (typical core diameters of 100 μm to 400 μm), it cannot be used for single mode fiber (typical mode diameters of 6 μm to 30 μm), because the SMA connector cannot provide the tolerance required to align to such a small spot.
One connector that can be used for single mode fibers is the FC/PC connector. However, this connector was designed for low powers, such as are used in telecommunications. The FC/PC connector cannot reliably be used above one Watt of power.
Another problem with the standard connectors is that they cannot connect fibers of different mode sizes. For example, the output of a single-mode fiber laser with a mode diameter of 6 μm cannot be connected to a large mode area fiber with a mode area of 30 μm.